PITTSBURGH (AP) — The 6-year-old daughter of a University of Pittsburgh medical researcher and the neurologist wife he’s accused of poisoning should continue to live with the victim’s parents until his trial, a judge ruled.

Allegheny County Judge David Cashman issued that order after a closed-door custody hearing involving Cianna Ferrante.

The girl’s 64-year-old father, Dr. Robert Ferrante, remains jailed without bond on a criminal homicide charge alleging he poisoned the girl’s mother, Dr. Autumn Klein, by lacing her energy supplement drink with cyanide in April.

Pittsburgh police charged Ferrante last month after revealing, among other clues, that Ferrante had purchased more than a half-pound of the poison using a university credit card just two days before his 41-year-old wife fell suddenly ill, even though the fast-acting toxin isn’t related to his research.

Ferrante has denied involvement in Klein’s death. Defense attorney William Difenderfer had said Ferrante remains “devastated” by it, but attorneys and other parties in the case are now subject to a gag order.

The girl has been in the custody of Klein’s parents, William and Lois Klein, of Towson, Md., since shortly before Ferrante was arrested.

County prosecutors have said the girl is a “material witness” in the criminal case and asked Cashman to prevented Ferrante from contacting her. Prosecutors haven’t said what kind of evidence the girl might offer, and the 11-page criminal complaint filed by Pittsburgh police offers few clues.

Although Wednesday’s custody hearing was closed, the custody order Cashman issued afterward and documents filed on behalf of the Kleins and Ferrante’s adult son, Michael Ferrante, of Boston, are public.

The Kleins sought a longer-term custody order in order to protect the girl from “nefarious attempts of father and his relatives to influence her testimony and memory relating to the events surrounding the death of her mother,” the grandparents’ attorney wrote.

The Kleins told police that after their daughter’s hospitalization and death “Ferrante has not allowed them to be alone with their grandchild,” which they found “strange” since they often watched the girl in the past.

Michael Ferrante, 30, and his 28-year-old wife, Nicole, sought custody of the girl, arguing they’re more age-appropriate guardians than the Kleins, who are in their 70s. Their attorney wrote that the couple would also “provide a positive atmosphere without criticizing the child’s father or mother and will insulate the child from the child’s father’s likely murder trial.”

But Cashman ruled the Ferrantes can’t claim custody under Pennsylvania law, which restricts such claims to parents, grandparents or those who have acted as a child’s “stand-in” parents.

Custody matters are normally handled by a family court judge, but Cashman has issued an order giving the court’s criminal division jurisdiction until Ferrante’s criminal case ends.